本文選題：蔣廟巖體　切入點(diǎn)：鋯石U-Pb定年　出處：《地球科學(xué)》2017年06期

【摘要】：江蘇省寧鎮(zhèn)地區(qū)位于長(zhǎng)江中下游沿江成礦帶的最東端,是長(zhǎng)江中下游成礦帶的重要組成部分,蔣廟巖體是寧鎮(zhèn)地區(qū)唯一的基性巖體.對(duì)此巖體進(jìn)行了鋯石U-Pb年代學(xué)、礦物化學(xué)、巖石地球化學(xué)和Sr-Nd-Hf同位素研究,討論了其成因及地幔源區(qū)性質(zhì).巖體主要由橄欖輝長(zhǎng)巖、角閃輝長(zhǎng)巖和輝石閃長(zhǎng)巖組成,其中輝石閃長(zhǎng)巖的鋯石LA-ICP-MS(laser ablation inductively coupled plasma mass spectrometry)U-Pb年齡為121±1Ma.鋯石εHf(t)值介于-2.9~-6.4.全巖地球化學(xué)研究顯示巖石樣品富鈉低鉀,富集輕稀土元素,重稀土元素虧損不明顯,富集大離子親石元素(如K、Ba、Sr等),虧損高場(chǎng)強(qiáng)元素(如Nb、Ta、Ti、Zr、Hf等).蔣廟基性侵入巖在長(zhǎng)江中下游地區(qū)中生代巖漿巖中具有最高的εNd(t)值以及最低的(87Sr/86Sr)i值,其Sr-Nd同位素組成介于軟流圈地幔(depleted MORB mantle,DMM)-富集巖石圈地幔(enriched mantleⅡ,EMⅡ)之間.研究認(rèn)為,蔣廟巖體應(yīng)來(lái)源于軟流圈地幔和富集巖石圈地幔的混合組分,可能有少量的俯沖板片物質(zhì)加入源區(qū),并在成巖過程中經(jīng)歷了一定程度的結(jié)晶分異.結(jié)合區(qū)域地質(zhì)、年代學(xué)、礦物學(xué)和地球化學(xué)資料,表明蔣廟巖體的形成可能與古太平洋板塊俯沖事件密切相關(guān).
[Abstract]:The Ningzhen area of Jiangsu Province is located at the easternmost end of the metallogenic belt along the Yangtze River in the middle and lower reaches of the Yangtze River, and is an important part of the metallogenic belt in the middle and lower reaches of the Yangtze River. The Jiangmiao rock body is the only basic rock body in the Ningzhen area. The zircon U-Pb chronology and mineralogical chemistry have been carried out. Petrogeochemistry and Sr-Nd-Hf isotopic studies are used to discuss its genesis and mantle origin. The rock body is mainly composed of olivine gabbro, hornblende gabbro and pyroxene diorite. Among them, the zircon LA-ICP-MS(laser ablation inductively coupled plasma mass spectrometry)U-Pb age of pyroxene diorite is 121 鹵1Ma.The zircon 蔚 HF t) value is between -2.9 ~ 6.4.The whole rock geochemical study shows that the rock samples are rich in sodium and low potassium, enriched in light rare earth elements, but not depleted in heavy rare earth elements. It is rich in large ion lithophile elements (such as Ki, Baer, Sr, etc., and depleted in high field strength elements, such as NbBU Tajiao TiTiZR, HF, etc.). The Jiangmiao basic intrusive rocks have the highest 蔚 Ndtl value in the Mesozoic magmatic rocks in the middle and lower reaches of the Yangtze River, and the lowest value of 87-Sr-86SrI. Its Sr-Nd isotopic composition is somewhere between the asthenospheric mantle depleted MORB mantletle- enriched mantle 鈪，

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